Kai Yang,Keding Chen,Xingdi Zhang,Shuyu Gao,Jichang Sun,Jin Gong,Jinchao Chai,Yun Zheng,Zhihong Liu,Honghua Wang
Polyvinylidene fluoride (PVDF) has unique electrochemical oxidation resistance and is the only binder for high-voltage cathode materials in the battery industry for a long time. However, PVDF still has some drawbacks, such as environmental limitations on fluorine, strict requirements for environmental humidity, weak adhesion, and poor lithium ion conductivity. Herein, the long-standing issues associated with high-voltage lithium cobalt oxide (LiCoO 2 ; LCO) are successfully addressed by incorporating phenolphthalein polyetherketone (PEK-C) and phenolphthalein polyethersulfone (PES-C) as binder materials. These binders have unexpected electrochemical oxidation resistance and robustness adhesion, ensure uniform coverage on the surface of LCO, and establish an effective and fast ion-conductive CEI/binder composite layer. By leveraging these favorable characteristics, electrodes based on polyarylether binders demonstrate significantly better cycling and rate performance than their counterparts using traditional PVDF binders. The fast ion-conductive CEI/binder composite layer effectively mitigates adverse reactions at the cathode–electrolyte interface. As anticipated, batteries utilizing phenolphthalein polyarylether binders exhibit capacity retention rates of 88.92% and 80.4% after 200 and 500 cycles at 4.5 and 4.6 V, respectively. The application of binders, such as polyarylether binders, offers a straightforward and inspiring approach for designing high-energy-density battery materials.
Sinan Zheng,Yang Wang,Bin Luo,Leilei Sun,Guosheng Duan,Zhean Bao,Li Gong,Jingyun Huang,Zhizhen Ye
Benefiting from features such as high-voltage platforms, superior energy density, and cost-effectiveness, Zinc-bromine flow batteries (ZBFBs) demonstrate significant potential for large-scale energy storage applications. However, their practical implementation faces critical challenges: sluggish Br 2 /Br − redox reactions and severe shuttle effects, which lead to diminished energy efficiency and self-discharge. Here, we develop an innovative electrochemical self-induced catalyst gel encapsulation strategy. Under electrochemical driving, the poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS, abbreviated as PES) catalyst spontaneously undergoes gelation and coating on carbon fibers, thereby forming a PES@C composite cathode with enhanced bromine conversion reversibility. This innovative strategy effectively addresses three critical challenges in existing ZBFBs: shuttle effect, low bromine utilization, and poor energy efficiency. PES@C with sulfur sites and C–O-C group enable efficient bromine/poly-bromide anchoring through strong polar interactions, effectively suppressing shuttling effects. Furthermore, the abundant active sites exhibit exceptional catalytic activity towards Br 2 /Br − redox reactions. This synergistic adsorption-catalysis mechanism significantly enhances the electrochemical performance of ZBFBs. The ZBFBs with PES@C achieve stable operation under ultrahigh current density (200 mA cm −2 ) and high areal capacity (40 mA h cm −2 ), delivering outstanding voltage efficiency (84.91%) and energy efficiency (81.78%). Notably, the proposed strategy demonstrates universal applicability for performance enhancement in various bromine-based battery systems, providing an efficient pathway to improve energy efficiency and cycling durability in bromine-based flow batteries.
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